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IP Subnet Mask Quick Cheat Sheet

Besides the fact that I am studying for another Microsoft test and staring at subnets all day long – I also get asked on a regular basis how many addresses can i get from a /24 subnet or what does 255.255.255.0 mean.

Let me break it down for you real quick like:

When you use 255.255.255.0 as your subnet you are limiting yourself to a network containing all the same ip’s except for the last number. Like 192.168.1.0 where the 0 changes. And using 255.255.0.0 Would limit you to the last two digits changing like 192.168.0.0 . Are you with me? It gets a little more complex with different subnets but here is a quick breakdown for you:

Remember though the number of IP addresses isn’t the number of computers that can be on the network. It’s usually off by 3 – with IPs reserved for the Network address, the Broadcast address, and the gateway.

The quickest way to understand subnetting is that subnetting is a binary AND operation of all the octets in your IP address with the subnet mask. subnet binary 255 (11111111) always allows the octet to pass thru and becomes the same number in the network address. performing an AND operation if the mask octet is less that 255 will yield a consistent number that will become the lowest number of the network address octet. A smaller mask octet number will yield a wider network range for the chosen IP address, and this number range is 256 minus the mask octet. For example, a mask of 255.255.254.0 will yield a 2 x 255 address range for the chosen IP address. Lowest number in the range is the network address and the highest is the broadcast address.

With Android becoming increasingly popular, it wouldn’t be surprising if Apple users demand i – OS 6 to be equipped with more widgets.
” Wait for i – Tunes to restore your device to i – OS 6 Beta 2. For Routers that have only fixed interfaces, the interface nomenclature is.

Besides the fact that I am studying for another Microsoft test and staring at subnets all day long - I also get asked on a regular basis how many addresses can i get from a /24 subnet or what does 255.255.255.0 mean.
Let me break it down for you real quick like: